| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Read bytes asynchronously."><meta name="keywords" content="rust, rustlang, rust-lang, AsyncBufRead"><title>AsyncBufRead in futures_io - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../normalize.css"><link rel="stylesheet" href="../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../ayu.css" disabled><link rel="stylesheet" href="../dark.css" disabled><link rel="stylesheet" href="../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../storage.js"></script><script defer src="sidebar-items.js"></script><script defer src="../main.js"></script><noscript><link rel="stylesheet" href="../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../favicon.svg"></head><body class="rustdoc trait"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle">☰</button><a class="sidebar-logo" href="../futures_io/index.html"><div class="logo-container"><img class="rust-logo" src="../rust-logo.svg" alt="logo"></div></a><h2></h2></nav><nav class="sidebar"><a class="sidebar-logo" href="../futures_io/index.html"><div class="logo-container"><img class="rust-logo" src="../rust-logo.svg" alt="logo"></div></a><h2 class="location"><a href="#">AsyncBufRead</a></h2><div class="sidebar-elems"><section><h3><a href="#required-methods">Required Methods</a></h3><ul class="block"><li><a href="#tymethod.consume">consume</a></li><li><a href="#tymethod.poll_fill_buf">poll_fill_buf</a></li></ul><h3><a href="#foreign-impls">Implementations on Foreign Types</a></h3><ul class="block"><li><a href="#impl-AsyncBufRead-for-%26%5Bu8%5D">&[u8]</a></li><li><a href="#impl-AsyncBufRead-for-%26mut%20T">&mut T</a></li><li><a href="#impl-AsyncBufRead-for-Box%3CT%3E">Box<T></a></li><li><a href="#impl-AsyncBufRead-for-Pin%3CP%3E">Pin<P></a></li></ul><h3><a href="#implementors">Implementors</a></h3></section><h2><a href="index.html">In futures_io</a></h2></div></nav><main><div class="width-limiter"><nav class="sub"><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1 class="fqn">Trait <a href="index.html">futures_io</a>::<wbr><a class="trait" href="#">AsyncBufRead</a><button id="copy-path" onclick="copy_path(this)" title="Copy item path to clipboard"><img src="../clipboard.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="srclink" href="../src/futures_io/lib.rs.html#251-298">source</a> · <a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span></div><div class="item-decl"><pre class="rust trait"><code>pub trait AsyncBufRead: <a class="trait" href="trait.AsyncRead.html" title="trait futures_io::AsyncRead">AsyncRead</a> { |
| fn <a href="#tymethod.poll_fill_buf" class="fnname">poll_fill_buf</a>(<br> self: <a class="struct" href="https://doc.rust-lang.org/nightly/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&mut </a>Self>,<br> cx: &mut <a class="struct" href="https://doc.rust-lang.org/nightly/core/task/wake/struct.Context.html" title="struct core::task::wake::Context">Context</a><'_><br> ) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/task/poll/enum.Poll.html" title="enum core::task::poll::Poll">Poll</a><<a class="type" href="https://doc.rust-lang.org/nightly/std/io/error/type.Result.html" title="type std::io::error::Result">Result</a><&[<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a>]>>; |
| <span class="item-spacer"></span> fn <a href="#tymethod.consume" class="fnname">consume</a>(self: <a class="struct" href="https://doc.rust-lang.org/nightly/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&mut </a>Self>, amt: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>); |
| }</code></pre></div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Read bytes asynchronously.</p> |
| <p>This trait is analogous to the <code>std::io::BufRead</code> trait, but integrates |
| with the asynchronous task system. In particular, the <code>poll_fill_buf</code> |
| method, unlike <code>BufRead::fill_buf</code>, will automatically queue the current task |
| for wakeup and return if data is not yet available, rather than blocking |
| the calling thread.</p> |
| </div></details><h2 id="required-methods" class="small-section-header">Required Methods<a href="#required-methods" class="anchor"></a></h2><div class="methods"><details class="rustdoc-toggle method-toggle" open><summary><section id="tymethod.poll_fill_buf" class="method has-srclink"><a class="srclink rightside" href="../src/futures_io/lib.rs.html#280">source</a><h4 class="code-header">fn <a href="#tymethod.poll_fill_buf" class="fnname">poll_fill_buf</a>(<br> self: <a class="struct" href="https://doc.rust-lang.org/nightly/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&mut </a>Self>,<br> cx: &mut <a class="struct" href="https://doc.rust-lang.org/nightly/core/task/wake/struct.Context.html" title="struct core::task::wake::Context">Context</a><'_><br>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/task/poll/enum.Poll.html" title="enum core::task::poll::Poll">Poll</a><<a class="type" href="https://doc.rust-lang.org/nightly/std/io/error/type.Result.html" title="type std::io::error::Result">Result</a><&[<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a>]>></h4></section></summary><div class="docblock"><p>Attempt to return the contents of the internal buffer, filling it with more data |
| from the inner reader if it is empty.</p> |
| <p>On success, returns <code>Poll::Ready(Ok(buf))</code>.</p> |
| <p>If no data is available for reading, the method returns |
| <code>Poll::Pending</code> and arranges for the current task (via |
| <code>cx.waker().wake_by_ref()</code>) to receive a notification when the object becomes |
| readable or is closed.</p> |
| <p>This function is a lower-level call. It needs to be paired with the |
| <a href="trait.AsyncBufRead.html#tymethod.consume"><code>consume</code></a> method to function properly. When calling this |
| method, none of the contents will be “read” in the sense that later |
| calling <a href="trait.AsyncRead.html#tymethod.poll_read"><code>poll_read</code></a> may return the same contents. As such, <a href="trait.AsyncBufRead.html#tymethod.consume"><code>consume</code></a> must |
| be called with the number of bytes that are consumed from this buffer to |
| ensure that the bytes are never returned twice.</p> |
| <p>An empty buffer returned indicates that the stream has reached EOF.</p> |
| <h5 id="implementation"><a href="#implementation">Implementation</a></h5> |
| <p>This function may not return errors of kind <code>WouldBlock</code> or |
| <code>Interrupted</code>. Implementations must convert <code>WouldBlock</code> into |
| <code>Poll::Pending</code> and either internally retry or convert |
| <code>Interrupted</code> into another error kind.</p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="tymethod.consume" class="method has-srclink"><a class="srclink rightside" href="../src/futures_io/lib.rs.html#297">source</a><h4 class="code-header">fn <a href="#tymethod.consume" class="fnname">consume</a>(self: <a class="struct" href="https://doc.rust-lang.org/nightly/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&mut </a>Self>, amt: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>)</h4></section></summary><div class="docblock"><p>Tells this buffer that <code>amt</code> bytes have been consumed from the buffer, |
| so they should no longer be returned in calls to <a href="trait.AsyncRead.html#tymethod.poll_read"><code>poll_read</code></a>.</p> |
| <p>This function is a lower-level call. It needs to be paired with the |
| <a href="trait.AsyncBufRead.html#tymethod.poll_fill_buf"><code>poll_fill_buf</code></a> method to function properly. This function does |
| not perform any I/O, it simply informs this object that some amount of |
| its buffer, returned from <a href="trait.AsyncBufRead.html#tymethod.poll_fill_buf"><code>poll_fill_buf</code></a>, has been consumed and should |
| no longer be returned. As such, this function may do odd things if |
| <a href="trait.AsyncBufRead.html#tymethod.poll_fill_buf"><code>poll_fill_buf</code></a> isn’t called before calling it.</p> |
| <p>The <code>amt</code> must be <code><=</code> the number of bytes in the buffer returned by |
| <a href="trait.AsyncBufRead.html#tymethod.poll_fill_buf"><code>poll_fill_buf</code></a>.</p> |
| </div></details></div><h2 id="foreign-impls" class="small-section-header">Implementations on Foreign Types<a href="#foreign-impls" class="anchor"></a></h2><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-AsyncBufRead-for-Box%3CT%3E" class="impl has-srclink"><a class="srclink rightside" href="../src/futures_io/lib.rs.html#518-520">source</a><a href="#impl-AsyncBufRead-for-Box%3CT%3E" class="anchor"></a><h3 class="code-header">impl<T: ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a> + <a class="trait" href="trait.AsyncBufRead.html" title="trait futures_io::AsyncBufRead">AsyncBufRead</a> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a>> <a class="trait" href="trait.AsyncBufRead.html" title="trait futures_io::AsyncBufRead">AsyncBufRead</a> for <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/boxed/struct.Box.html" title="struct alloc::boxed::Box">Box</a><T></h3></section></summary><div class="impl-items"><section id="method.poll_fill_buf" class="method trait-impl has-srclink"><a class="srclink rightside" href="../src/futures_io/lib.rs.html#519">source</a><a href="#method.poll_fill_buf" class="anchor"></a><h4 class="code-header">fn <a href="#tymethod.poll_fill_buf" class="fnname">poll_fill_buf</a>(<br> self: <a class="struct" href="https://doc.rust-lang.org/nightly/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&mut </a>Self>,<br> cx: &mut <a class="struct" href="https://doc.rust-lang.org/nightly/core/task/wake/struct.Context.html" title="struct core::task::wake::Context">Context</a><'_><br>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/task/poll/enum.Poll.html" title="enum core::task::poll::Poll">Poll</a><<a class="type" href="https://doc.rust-lang.org/nightly/std/io/error/type.Result.html" title="type std::io::error::Result">Result</a><&[<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a>]>></h4></section><section id="method.consume" class="method trait-impl has-srclink"><a class="srclink rightside" href="../src/futures_io/lib.rs.html#519">source</a><a href="#method.consume" class="anchor"></a><h4 class="code-header">fn <a href="#tymethod.consume" class="fnname">consume</a>(self: <a class="struct" href="https://doc.rust-lang.org/nightly/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&mut </a>Self>, amt: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>)</h4></section></div></details><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-AsyncBufRead-for-%26mut%20T" class="impl has-srclink"><a class="srclink rightside" href="../src/futures_io/lib.rs.html#522-524">source</a><a href="#impl-AsyncBufRead-for-%26mut%20T" class="anchor"></a><h3 class="code-header">impl<T: ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a> + <a class="trait" href="trait.AsyncBufRead.html" title="trait futures_io::AsyncBufRead">AsyncBufRead</a> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a>> <a class="trait" href="trait.AsyncBufRead.html" title="trait futures_io::AsyncBufRead">AsyncBufRead</a> for <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&mut </a>T</h3></section></summary><div class="impl-items"><section id="method.poll_fill_buf-1" class="method trait-impl has-srclink"><a class="srclink rightside" href="../src/futures_io/lib.rs.html#523">source</a><a href="#method.poll_fill_buf-1" class="anchor"></a><h4 class="code-header">fn <a href="#tymethod.poll_fill_buf" class="fnname">poll_fill_buf</a>(<br> self: <a class="struct" href="https://doc.rust-lang.org/nightly/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&mut </a>Self>,<br> cx: &mut <a class="struct" href="https://doc.rust-lang.org/nightly/core/task/wake/struct.Context.html" title="struct core::task::wake::Context">Context</a><'_><br>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/task/poll/enum.Poll.html" title="enum core::task::poll::Poll">Poll</a><<a class="type" href="https://doc.rust-lang.org/nightly/std/io/error/type.Result.html" title="type std::io::error::Result">Result</a><&[<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a>]>></h4></section><section id="method.consume-1" class="method trait-impl has-srclink"><a class="srclink rightside" href="../src/futures_io/lib.rs.html#523">source</a><a href="#method.consume-1" class="anchor"></a><h4 class="code-header">fn <a href="#tymethod.consume" class="fnname">consume</a>(self: <a class="struct" href="https://doc.rust-lang.org/nightly/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&mut </a>Self>, amt: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>)</h4></section></div></details><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-AsyncBufRead-for-Pin%3CP%3E" class="impl has-srclink"><a class="srclink rightside" href="../src/futures_io/lib.rs.html#526-538">source</a><a href="#impl-AsyncBufRead-for-Pin%3CP%3E" class="anchor"></a><h3 class="code-header">impl<P> <a class="trait" href="trait.AsyncBufRead.html" title="trait futures_io::AsyncBufRead">AsyncBufRead</a> for <a class="struct" href="https://doc.rust-lang.org/nightly/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a><P><span class="where fmt-newline">where<br> P: <a class="trait" href="https://doc.rust-lang.org/nightly/core/ops/deref/trait.DerefMut.html" title="trait core::ops::deref::DerefMut">DerefMut</a> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a>,<br> P::<a class="associatedtype" href="https://doc.rust-lang.org/nightly/core/ops/deref/trait.Deref.html#associatedtype.Target" title="type core::ops::deref::Deref::Target">Target</a>: <a class="trait" href="trait.AsyncBufRead.html" title="trait futures_io::AsyncBufRead">AsyncBufRead</a>,</span></h3></section></summary><div class="impl-items"><section id="method.poll_fill_buf-2" class="method trait-impl has-srclink"><a class="srclink rightside" href="../src/futures_io/lib.rs.html#531-533">source</a><a href="#method.poll_fill_buf-2" class="anchor"></a><h4 class="code-header">fn <a href="#tymethod.poll_fill_buf" class="fnname">poll_fill_buf</a>(<br> self: <a class="struct" href="https://doc.rust-lang.org/nightly/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&mut </a>Self>,<br> cx: &mut <a class="struct" href="https://doc.rust-lang.org/nightly/core/task/wake/struct.Context.html" title="struct core::task::wake::Context">Context</a><'_><br>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/task/poll/enum.Poll.html" title="enum core::task::poll::Poll">Poll</a><<a class="type" href="https://doc.rust-lang.org/nightly/std/io/error/type.Result.html" title="type std::io::error::Result">Result</a><&[<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a>]>></h4></section><section id="method.consume-2" class="method trait-impl has-srclink"><a class="srclink rightside" href="../src/futures_io/lib.rs.html#535-537">source</a><a href="#method.consume-2" class="anchor"></a><h4 class="code-header">fn <a href="#tymethod.consume" class="fnname">consume</a>(self: <a class="struct" href="https://doc.rust-lang.org/nightly/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&mut </a>Self>, amt: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>)</h4></section></div></details><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-AsyncBufRead-for-%26%5Bu8%5D" class="impl has-srclink"><a class="srclink rightside" href="../src/futures_io/lib.rs.html#552-554">source</a><a href="#impl-AsyncBufRead-for-%26%5Bu8%5D" class="anchor"></a><h3 class="code-header">impl <a class="trait" href="trait.AsyncBufRead.html" title="trait futures_io::AsyncBufRead">AsyncBufRead</a> for &[<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a>]</h3></section></summary><div class="impl-items"><section id="method.poll_fill_buf-3" class="method trait-impl has-srclink"><a class="srclink rightside" href="../src/futures_io/lib.rs.html#553">source</a><a href="#method.poll_fill_buf-3" class="anchor"></a><h4 class="code-header">fn <a href="#tymethod.poll_fill_buf" class="fnname">poll_fill_buf</a>(<br> self: <a class="struct" href="https://doc.rust-lang.org/nightly/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&mut </a>Self>,<br> _: &mut <a class="struct" href="https://doc.rust-lang.org/nightly/core/task/wake/struct.Context.html" title="struct core::task::wake::Context">Context</a><'_><br>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/task/poll/enum.Poll.html" title="enum core::task::poll::Poll">Poll</a><<a class="type" href="https://doc.rust-lang.org/nightly/std/io/error/type.Result.html" title="type std::io::error::Result">Result</a><&[<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a>]>></h4></section><section id="method.consume-3" class="method trait-impl has-srclink"><a class="srclink rightside" href="../src/futures_io/lib.rs.html#553">source</a><a href="#method.consume-3" class="anchor"></a><h4 class="code-header">fn <a href="#tymethod.consume" class="fnname">consume</a>(self: <a class="struct" href="https://doc.rust-lang.org/nightly/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&mut </a>Self>, amt: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>)</h4></section></div></details><h2 id="implementors" class="small-section-header">Implementors<a href="#implementors" class="anchor"></a></h2><div id="implementors-list"></div><script src="../implementors/futures_io/if_std/trait.AsyncBufRead.js" data-ignore-extern-crates="alloc,core,std" async></script></section></div></main><div id="rustdoc-vars" data-root-path="../" data-current-crate="futures_io" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
